The description of the prior art refers to folding devices in which two parts, designated as A and B below, are rotatably interconnected on one of its side, while, on the other side, a locking mechanism is provided that acts only on this side and braces the two parts A and B relative to each other. In the process, the disclosure refers to those embodiments that exhibit, for the purpose of blocking, on the side of the locking mechanism inside one part, in the following inside part A, an axis on which a locking assembly having elements for locking is rotatably arranged, the two parts A and B being braced relative to each other by rotating a locking lever that is part of the locking assembly. Here, the locking assembly is supported on the axis arranged in part A, on which it is mounted rotatably, and pushes or pulls part B against part A. The disclosure finally refers to all embodiments that exhibit a clamping surface that runs eccentrically relative to the axis of rotation of the locking assembly, against which parts A and B are braced relative to each other.
In U.S. Pat. No. 6,523,223 B2, U.S. Pat. No. 7,198,281 B2, WO 2009/152 768 A1 and in the first embodiment of CN 201 626 517 U, the locking lever exhibits the clamping surface that runs eccentrically relative to its own axis of rotation.
It is a disadvantage of these embodiments, that the locking mechanism exhibits two different axes of rotation, i.e. the axis of rotation of the locking lever and the axis of rotation, that is different therefrom, of the locking assembly. Both rotary joints have to be manufactured having the corresponding strength and require a multiplicity of components. On top of this it is disadvantageous that the pressure that the eccentric clamping surface of the locking lever exerts on part B, cannot be set or can be set only within narrow limits independently of the closing angle of the locking lever owing to the construction.
It is a further disadvantage of the embodiment in WO 2009/152 768 A1, that the force that is exerted by the eccentric outer cylinder surface does not act directly, but laterally via the additional locking element on part B.
In WO 2007/113 179 A1, the locking lever likewise exhibits the clamping surface that runs eccentrically relative to its own axis of rotation. It is a disadvantage that the distance between the axis of rotation of the locking lever and the bolt in the locking state cannot be set and thus the force acting from the locking lever on part B is a direct function of the closing angle of the locking lever.
In CN 201 580 496 U, the locking assembly contains a clamping element that is supported on part B via a round bolt and rotates around the round bolt and exhibits a clamping surface that runs eccentrically relative to this axis of rotation. The clamping element is arranged rotatably in the locking lever.
It is again a disadvantage that the locking assembly exhibits two axes of rotation, i.e. the axis of rotation of the clamping element and the axis of rotation, that is different therefrom, of the locking assembly, both of which having to be designed with the corresponding strength and requiring a multiplicity of components.
In CN 201 559 768 U, a clamping element is rotatably arranged in part B and exhibits the clamping surface that runs eccentrically relative to the axis of rotation of the locking assembly. Here, too, it is a disadvantage that two axes of rotation are required that have to be designed with the corresponding strength, i.e. the axis of rotation, arranged in part B, of the clamping element and the axis of rotation, that is different therefrom and is arranged in part B, of the locking assembly.
CN 201 626 519 U, CN 201 254 246 Y and the second embodiment of CN 201 626 517 U reveal folding devices where part B exhibits a clamping surface on the side of the locking mechanism, which runs eccentrically relative to the axis of rotation of the locking assembly and is arranged firmly in part B, the locking mechanism exhibiting only one axis of rotation and the rotation of the locking assembly about its axis generating an increasing bracing between part A and part B.
However, it is a disadvantage of these embodiments
a. that the radius of curvature of the clamping surface and the width, that can be used for clamping, of the clamping surface are so small owing to the construction, that the usable clamping displacement, i.e. the angle that the locking lever travels from the first contact of part B to the braced state, is very small, which places high requirements on the precise radial positioning of the clamping surface relative to the axis of rotation of the locking lever by means of the setting screws that are present and on the fixation of the clamped position of the locking lever. In the braced state, the closing angle of the locking lever has to be set very precisely and fixed by securing means and stops, so as to achieve and maintain the required bracing between parts A and B. As a consequence, the locking lever can also not be moved beyond the point of highest bracing to achieve a self-securing position, as else the clamping force would decrease considerably,b. that owing to the construction, parts A and B exhibit in their center additional elevations and oppositely-identical depressions so that parts A and B, in the folded state, can be positioned relative to each other with sufficient accuracy and mutual shifting of parts A and B relative to their common axis of rotation and/or orthogonally to their common axis of rotation is prevented. This has the disadvantage that parts A and B, owing to the construction, in each case have to exhibit a plate that connects the axis of rotation, arranged on one side, of the folding device to the clamping elements that are arranged on the opposite side (this is also valid for CN 201 580 496 U, CN 201 559 768 U),c. that parts A and B, owing to the construction, do not engage into each other on the side of the locking mechanism in the folded state and that therefore the locking lever must prevent the mutual displaceability of parts A and B in the direction of their common axis of rotation on this side in that the locking lever exhibits on both sides two arms having end faces that enclose one arm of part B and thus prevent the movability of part B toward part A in the direction of their common axis of rotation on the side of the clamping surfaces of the folding device, as a result of which however axial tolerances of the mounting of the locking lever can lead to instabilities of the clamping connection (is also valid for CN 201 559 768 U).
In CN 201 626 519 U and in the second embodiment of CN 201 626 517 U, there is arranged in part B a separate clamping element having a round head that functions as a clamping surface. An additional disadvantage of this embodiment that bracing between parts A and B only takes place by point contact of the clamping elements and that there is a risk that the two clamping elements evade the bracing action by slight lateral movements.
The two embodiments of the folding devices illustrated in CN 201 626 517 U serve to connect tubes of circular or at least oval cross-section. For this reason, they are not suitable for connecting parts having box-shaped profiles. In both embodiments of CN 201 626 517, parts A and B exhibit at their circumference additional upstanding walls that limit a mutual movement of parts A and B orthogonal to their axis of rotation. This again requires that, owing to the construction, parts A and B in each case have to exhibit a plate that connects the axis of rotation, arranged on one side, of the folding device to the clamping elements arranged on the opposite side.